I would have guessed the guard on the left who holds the silver platter or salver to deliver the head of John the Baptist to Salome to bring to Herod might be by Leonardo.. To me he looks more like a guardian angel than a guard, especially with his head bent down toward John and his hand held up as if to bless him. I seem to remember such an angel in one of Leonardo's paintings somewhere (Madonna of the Rocks? Or the face of John the Beloved Disciple, in the Last Supper - the one that Dan Brown tried to turn into Mary Magdalene?!LOL). With his knees slightly bent and crossed, he looks llke he is dancing a gavotte, and with his whole body turned in a graceful contrapossto pose, he looks quite feminine, or effeminate. In the ful-size? detail in the magazine article, his face looks even more feminine,and also pitying. I've heard that Leonardo was gay, and this would be in line with that. In short, if he/she is a soldier, he's a soldier in drag?

As to which soldier might also be by Leonardo, I can only take a wild guess: Might it be te figure of John the Baptist? The only clue for me, besides his curly hair, would be the folds of his garment, which I seem to remember Leonardo liking to draw in his sketches?